This invention relates generally to the starting of gas discharge lamps, and more particularly concerns overcoming problems relating to such starting.
Gas discharge lamps such as mercury vapor lamps have come into widespread use, two examples being sources of ultraviolet light employed in print reproduction, and street lamps. Although such lamps are clean and efficient devices, as compared with carbon arc lights, they have presented two long standing problems. First, they require objectionably long warm-up times, i.e up to about 5 minutes in certain cases; and secondly, there is the practical impossibility of re-starting a warmed-up mercury vapor lamp (should it be even momentarily turned off) until it cools. Therefore, for repetitive on-off duty, it has been the practice to leave the lamp on all the time, and resort to a mechanical shutter which is moved to control exposure. Such shutters, however, are subject to mechanical failure, and resultant prolonged human exposure to a mercury vapor lamp in ON condition can cause serious damage to the eyes and skin.